In many cases it is required to measure the flow rate and volume of liquids and gasses. In many applications, the flow rate may be very low (several ml/h), in other cases the flow rate may be very high (cubic meters per second) and in some cases the flow rate may not be stable and can fluctuate over time. Furthermore, measuring volumetric flow rate of gas introduces a special challenge since gases are compressible and change their volume when placed under pressure or different temperature. A volume of gas under one set of pressure and temperature conditions is not equivalent to the same gas under different conditions.
Applications for accurate fluid flow measurement exist in analysis, such as HPLC (High Performance Liquid Chromatography), in the semiconductor industry such as for precise material dosing, in the medical field such as for accurate drug delivery, in automotive such as for gasoline flow measurement.
However, in some applications there is a need for measuring fluid flow in a very wide dynamic range while maintaining absolute measurement accuracy. For example, measuring the water flow rate at two points along a water line and comparing the readings from both measurements can indicate the existence of a leak in the line. In order to be able to identify very small leaks, the flow meter is supposed to have absolute accuracy at the entire measuring range of the meter. If the accuracy of the flow meter would be a relative accuracy (a percentage of the flow), then at low flow rates small leaks could be identified, but at high flow rates only large leaks will be identifiable. For instance, if the accuracy of the flow meter is 0.1%, then at flow rates of 1 Liter/minute a leak of 1 ml/minute can be identified, but at a flow rate of 1,000 Liter/minute only leaks as large as 1 Liter/minute will be identified.
Accordingly, there is a need in the field of fluid flow measuring for flow measuring systems, apparatuses, devices and methods that may enable and facilitate the measuring of fluid flow, based on the displacement of known fluid amounts; and may allow for the flow of liquids and/or gases to be metered under various conditions and for various applications, while providing substantially accurate flow estimation, possibly with absolute accuracy (i.e. accuracy that is not dependent on the flowing fluid amount).